According to Fred H. Detmers, Technicolor's domestic sales manager, in the June-July 1968 issue of "Films in Review," this was the last film shot in the Three-Strip Technicolor process; however, according to a number of other reliable sources, Foxfire (1955) holds that distinction.
Parts of the film were shot in Colorado River, Professor Valley, and Courthouse Wash in Utah. The film was also shot on location in Moab, Utah, by the Colorado River.
Filming began on 3 June 1953, the same day as Universal's The Glenn Miller Story (1954). The two films were the first movies made at Universal for four weeks.
The film begins with the following written foreword: "During the war between Maximilian and Juarez in 1865, there was a small territory on the Mexican side of the Rio Grande River known as Zona Libre-'Free Zone.' It was dominated by a man who called himself General Eduardo Calleja and he made it a haven for any man outside the law. This is the story of Zona Libre."